The purpose of the proposed research project is four fold: 1) To quantitate by radioimmunoassay hormonal content (GH, TSH, ACTH, FSH, LH, and LTH) of the human fetal pituitary gland and hypothalamus from early gestation until 24 weeks and correlate this with age and sex, 2) To evaluate the hormonal releasing and/or synthesizing properties of various synthetic hypothalamic hormones, 3) To study the dynamics of pituitary hormonal secretion in vitro, 4) To study maternal-fetal endocrine relationships.